I think because WordPress.org is heading into a direction of being a website builder itself, it will naturally hurt developers/businesses who make their living off of it.
Yeah, cool and exciting designs might still have a market, but for blogs, magazine sites, portfolios - that ~$50 for a premium theme might be better spent elsewhere.
I don't know if you're familiar with Webflow[0], but it started out as yet another website builder. And, in recent years they have added so many features and layout templates that I once got confused seeing the "Made with Webflow" badge on a landing page. It had all modern features like smooth page transitions, svg animations, cool gallery effects, etc,. You know, the things people pay that $50 for.
If this happens, or rather when it happens, maybe Automattic will have to think hard about what it wants the future to look like.
[0]: https://webflow.com/
And I must say, even though I have developed themes in the past, I'd prefer to see Gutenberg succeed in making most themes irrelevant. Themes that can be customised without PHP entirely seem to me to be a good solution to a lot of people's complaints about the untidy boundary between plugins and themes.
I am only familiar with Webflow from people who say "I've been trying to do this in Webflow but I'd prefer if we could do it in Wordpress".
But -- considering patterns can be used by every third party theme in an open source CMS -- how do you get to talking about developers unionizing (that is, under threat from some corporate entity) and Automattic taking over that business from there?
The reason I read it like a corporate big bad wolf fantasy is that you wrote it like one.